Process for sizing cellulose fibers

ABSTRACT

The present invention relates to a process for the sizing of materials containing cellulosic fibers (e.g. paper) by the use of carbamoyl chlorides.

United States Patent [19m Helmer et a1.

PROCESS FOR SIZING CELLULOSE FIBERS Inventors: Karin Ulla Elisabet Helmer, Solna;

Alf Ragnar Reuterhall, Gustavsberg, both of Sweden Assignee: Kemanord AB, Stockholm, Sweden Filed: July 14, 1972 Appl. No.: 271,858

Foreign Application Priority Data References Cited UNITED STATES PATENTS 4/1935 Nathansohn 8/120 June 3, 1975 2,099,363 1l/1937 l-leckert 162/179 2,270,658 l/1942 Linnhoff 8/120 3,238,010 3/1966 Habib et a]. 162/168 3,501,523 3/1970 Sayigh et al 260/544 0 FOREIGN PATENTS OR APPLICATIONS 804,504 1958 United Kingdom 162/158 OTHER PUBLICATIONS Casey, Pulp & Paper Vol. 11, 2nd Ed., p. 1072.

Primary ExaminerS. Leon Bashore Assistant ExaminerPeter Chin Attorney, Agent, or F irmFred Philpitt [5 7] ABSTRACT The present invention relates to a process for the sizing of materials containing cellulosic fibers (e.g. paper) by the use of carbamoyl chlorides.

14 Claims, No Drawings PROCESS #FOR SIZING CELLULOSE FIBERS BACKGROUND Sizing refers to the treatment of either cellulosic pulp fibers or an already formed cellulosic material with chemicals which control the wettability and surface properties of the final cellulosic product.

Paper frequently is sized with resinates which are fixed to the cellulose fibers by means of aluminum sulphate (alum). Another well known sizing agent which is fixed by means of reacting with the hydroxyl groups of the cellulose is based on alkyl ketene dimers. This agent is usually added to the stock dispersed in a cationic emulsifier. Alkylketene dimers have certain advantages over resinates. One advantage is that the pH of the stock is kept within the range of 7 8 compared to a pH range of 4.5 6.5 which is used when the resinates are used as sizes which among other things imparts improved aging properties to the paper and makes it possible to use alkaline fillers, such as calcium carbonate. Furthermore, considerably lesser amounts of ketene dimers are required to obtain a certain degree of hydrophobicity and the sizing thus obtained is permanent. Moreover the paper will have improved resistance to lactic acid, ink, etc.

A disadvantage when employing alkylketene dimers that no complete sizing effect is achieved until curing of the material for example, by storing at room temperature for about 48 hours or by heating to a temperature of 100C for minutes. Another disadvantage is that the sizing with alkylketene dimers is sensitive to alum present in the stock.

It also has been previously known to employ anhydrides of carboxylic acids as sizing agents, such as anhydrides of stearic acid or alkyl succinic acid. Said 'anhydrides do not have any of the above mentioned disadvantages that are encountered when employing resinates and ketene dimers, but greater amounts of the anhydride additives are required in order to achieve the same sizing effect as with the ketene dimers. In order to enhance the sizing effect it is common to add catalysts to the anhydrides so these catalysts are called siz- ,ing promoters and are used in relatively large amounts in combination with the anhydrides.

THE INVENTION BROADLY where R is an organic, hydrophobic hydrocarbon group comprising 8 40 carbon-,iatq ms and R is hydrogen, lower alkyl or has thesiam ejaning as R THE MATERIALS CONTAII I NCi. CELLULOSIC FIBERS The cellulosic fibers can be present in the form of a water suspension or in a more concentrated form, such as paperboard, fiberboard, 'or particle board, or they canbe included or admixed with other materials such as semi-synthetic paper containing plastics in addition to the cellulosic fibers.

THE CARBAMOYL CHLORIDE As noted above, the carbamoyl chloride has the general formula R o l N (3 where R is an organic, hydrophobic hydrocarbon group comprising 8 40 carbon atoms and R is hydro gen, lower alkyl or has the same meaning as R Examples of suitable hydrophobic groups are (a) a higher alkyl having between 8 and 40 carbon atoms (such as decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, octadecyl, tetracosy], and pentacosyl although those having about 12 30 carbon atoms are generally preferred, (b) the corresponding alkenyl groups having between 8 and 40 carbon atoms (such as decenyl, tridencenyl, heptadecenyl, octadecenyl, eicosenyl, tricosenyl etc.) (0) aralkyl, alkaryl, and alkyl substituted cycloalkyl having at least 8 carbon atoms (e.g. 4-tert.butylphenyl, octylphenyl, dinonylphenyl, dodecylphenyl, tridecylphenyl, pentadecylphenyl, octadecylphenyl, heneicosylphenyl, nonylcyclopropyl, dodecylcyclobutyl, tridecylcyclopentyl, tetradecylcyclohexyl, pentadecylcycloheptyl, octadecyl cyclohexyl etc.) and (d) any of the aforementioned alkyl alkenyl alkaryl and alkylcycloalkyl groups containing noninterfering, inert substituents. Of the inert substituents may be mentioned ether, carboalkoxy, alkyloxy, aryloxy, arylalkyloxy, keto(carbonyl)-tert. amide groups etc. Examples of radicals which should not be present to any great extent in the hydrophobic group may be mentioned e.g. hydroxyl groups, primary and secondary amino groups, unstable halogenes, and carboxyl groups or other acidic groups. To those Skilled in the art it is obvious which groups should be employed if undesired side reactions are to be avoided.

R preferably is an alkyl group comprising 12 30 carbon atoms and R is hydrogen; lower alkyl or has the same meaning as R The carbamoyl chlorides can be prepared according to known methods for instance by phosgenisation of the corresponding amines.

The advantages of the present invention are not dependent on what method is chosen to bring the carbamoyl chloride into contact with the cellulosic fibers. According to one method an aqueous suspension of cellulose fibers can be brought into contact with the carbamoyl chloride, which optionally can be dispersed in a suitable way. A solution or dispersion of the carbamoyl chloride chloroformate also can be brought into contact with a material containing cellulose fibers, such as paper.

The carbamoyl chlorides which are employed in the process of the present invention show a certain cationic activity and consequently retention to the cellulose fibers. Thus for certain purposes some additional retention agent may be omitted, e.g. for surface sizing or dipping concentrated cellulose fibcrs such as paper board,

particle board, etc. However, when the carbamoyl chloride is added to an aqueous suspension of cellulose fibers it is frequently desirable to employ a dispersion of the carbamoyl chlorides, and thus use an emulsifier in combination with the carbamoyl chloride compounds. For the preparation of a dispersion an emulsifier having anionic, cationic or nonionic properties or a mixture of these may be used. Especially preferred emulsifiers are the cationics, e.g. polyethylene imines,

4 tioned (at 20C and 65% relative humidity). The sheets then were impregnated by submerging them in a solution of 0.1% of substituted carbamoyl chloride in benzene for a few seconds and the excess of the solution was adsorbed. The impregnated sheets were dried at a temperature of 60C for 40 minutes and cured at 105 for 30 minutes. After conditioning the Cobb-number was determined according to the norm SCAN-P 12:64, which is a measure of the water absorbtivity of the polyalkylene polyamide resins, cationic starches etc. A 10 sheets. (The Cobb number for unsized paper is 100).

Type of melting point sizing agent Cobb,

substrtuent C based on weight g/m of dry fibers R, CH 1 w m. 67-69 0.015 20 R,=R-;=C,,,H 56-58 0.015 18 R2 llt tlil R Cyclohexyl 54-56 0.015 22 R2 m zn R phenyl 101-103 0.015 22 R2 CH: R, CH,-,(CH O(CHzl;; 39-42 0.020 24 R2 CH3 R, o l-1,, 20 0.20 21 R CH, R c,,1-1 20 0.05 22.5

special type of emulsion agent showing a good reten- EXAMPLE 2 tion to the fibers are quertones or aminohydrochlorides containing at least one alkyl group having 8 22 carbon atoms, such as dimethyldistearyl aminochloride or dimethylstearyl aminohydrochloride. The amount of the emulsifier should exceed 0.05% by weight based on the dry fibers, and preferably 0.1 10% by weight based on the dry fibers.

The carbamoyl chlorides according to the invention are employed in an amount exceeding 0.001 percent by weight based on the dry fibers by addition to the stock of fibers or by surface sizing of paper. The upper limit is not critical and is only limited by economical considerations. Preferably the amount of the carbamoyl chloride should fall within the range of from 0.001 to 5 percent by weight, most preferably 0.005 to 0.5 percent by weight based on the dry fibers. The fiber suspension or the concentrated fibers may also contain other additives commonly used in the manufacturing of paper, paperboard, fiberboard, particle board, etc. such as alum, fillers, pigments, retention agents, foam quentching agents, etc.

The present invention will now be described more in detail in the following examples which are given for illustration but are not intended to restrict the invention. Percentages and parts are by weight, unless otherwise specified.

EXAMPLE 1 Unsized paper sheets having a surface weight of about 70 g/m were formed from a bleached sulphate pulp beaten to about SR at a pH of 8.0 in a laboratory sheet machine. The sheets were dried and condi- 10 g of a carbamoyl chloride R R C ,,H were melted at 60C and then g distilled water (60 C) were added during homogenization for 5 minutes. The emulsion was thereupon rapidly cooled to 25C to give a stable dispersion.

EXAMPLE 3 10 g of a carbamoyl chloride R R C H and 0.5 g of a stearylamine hydrochloride were melted together at 60C, then 89.5 g of distilled water (60C) were added during homogenization for 5 minutes. The emulsion was rapidly cooled to 25C to give a stable dispersion.

EXAMPLE 4 EXAMPLE 5 10 g of carbamoyl chloride R R C l-l were melted and then 90.0 g of distilled water (60C) containing 0.5 g ofa water-soluble cationic polyacrylamide -were added during the homogenization for 5 minutes.

The emulsion then was rapidly cooled to 25C to give a stable dispersion. The obtained dispersions thereafter were used as sizing agents for paper in the same manner as described in Example 1. The results are shown in the following table: (The Cobb number for unsized paper is 100).

A dispersion as defined in example 2 was added to a suspension of cellulose fibers in water together with a cationic polyacrylamide having a molecular weight of more than one million.

EXAMPLE 7 A dispersion as defined in example 2 was added to a suspension of cellulose fibers in water together with an anionic polyacrylamide having a molecular weight of more than one million.

' EXAMPLE 8 A dispersion as defined in example 2 was added together with a cationic polyacrylamide having a high molecular weight to a suspension of cellulose fibers in water pre-treated with an anionic polyacrylamide having a molecular weight of more than one million. The cellulose fiber suspension according to examples 6-8 were then drained and sheets were produced in a laboratory sheet machine. The sheets were dried for 40 minuets at 60C and were cured for 30 minutes at 105C. After conditioning, the Cobb-number according to the norm SCAN-P 12:64 was determined. The results are shown in the following table:

The tests show that no substantial improvement in siz ing was obtained by adding a retention agent. (The Cobb number for unsized paper is 100).

EXAMPLE 9 In manufacturing of a porous fiberboard 0.20% of methylstearyl carbamoyl chloride were added to the stock based on the dry fiber weight. The board panels were dried for 2 hours at 20C 160C at a continuously elevating temperature. v

The water absorption of the board panels was deter- 1 mined according to the norm SlS-235105 whereby test specimens having the dimensions of 100 X 100 X 10 mm were submerged in water for 2 hours. The standard rate of absorption during large scale production of boards varied from 155 to 300% depending on the curing condition. The following results were obtained water absorption Reference Sized board 35 as described above What we claim is:

l. A process for sizing cellulose fibers or material containing cellulosic fibers wherein the cellulose fibers are brought into contact with at least 0.001% by weight based upon the weight of the dry cellulose fibers of a carbamoyl chloride having a general formula N C R2 Cl wherein R is an organic, hydrophobic hydrocarbon group containing 8-40 carbon atoms and R is selected from the group consisting of hydrogen, lower alkyl and organic, hydrophobic hydrocarbon group containing 8-40 carbon atoms.

2. A process as set forth in claim 1 wherein R is an alkyl group comprising 12-30 carbon atoms and R is selected from the group consisting of hydrogen, lower alkyl, and organic, hydrophobic hydrocarbon group containing 53-40 carbon atoms.

3. The process of claim 1 wherein R and/or R contain an inert substituent selected from the group of ether, carboalkoxy, alkyloxy, aryloxy, arylalkyloxy, and keto(carbonyl)-tert.amide groups.

4. The process of claim 1 wherein the amount of said carbamoyl chloride is within the range of from 0.001 to 5% by weight based upon the weight of dry cellulose fibers. i

5. The process of claim 1 wherein the amount of said carbamoyl chloride is within the range of from 0.005 to 0.5% by weight based upon dry cellulose fibers.

6. The process of claim 1 wherein both R and R are 1a 31- 7. The process of claim 1 wherein both R and R are 12 2s- 8. The process of claim 1 wherein said fibers are brought into contact with an aqueous dispersion of said carbamoyl chloride and an emulsifier in an effective emulsifying amount.

9. The process of claim 8 wherein said emulsifier is a cationic compound.

10. Cellulose fibers or material containing cellulosic fibers sized with a carbamoyl chloride having a general formula R2 Cl wherein R is an organic, hydrophobic hydrocarbon group containing 8-40 carbon atoms and R is selected from the group consisting of hydrogen, lower alkyl and organic, hydrophobic hydrocarbon group containing 8-40 carbon atoms, and wherein the amount of said 8 0.5% by weight based upon the weight of dry cellulose fibers.

13. The cellulose fiber or material containing cellulosic fibers of claim 10 which further includes an emulsifier.

14. The cellulose fiber or material containing cellulosic fibers of claim 13 wherein said emulsifier is a cationic emulsifier. 

1. A PROCESS FOR SIZING CELLULOSE FIBERS OR MATERIAL CONTAINING CELLULOSIC FIBERS WHEREIN THE CELLULOSE FIBERS ARE BROUGHT INTO CONTACT WITH AT LEAST 0.001% BY WEIGHT BASED UPON THE WEIGHT OF THE DRY CELLULOSE FIBERS OF A CARBAMOYL CHLORIDE HAVING A GENERAL FORMULA
 1. A process for sizing cellulose fibers or material containing cellulosic fibers wherein the cellulose fibers are brought into contact with at least 0.001% by weight based upon the weight of the dry cellulose fibers of a carbamoyl chloride having a general formula
 2. A process as set forth in claim 1 wherein R1 is an alkyl group comprising 12-30 carbon atoms and R2 is selected from the group consisting of hydrogen, lower alkyl, and organic, hydrophobic hydrocarbon group containing 8-40 carbon atoms.
 3. The process of claim 1 wherein R1 and/or R2 contain an inert substituent selected from the group of ether, carboalkoxy, alkyloxy, aryloxy, arylalkyloxy, and keto(carbonyl)-tert.amide groups.
 4. The process of claim 1 wherein the amount of said carbamoyl chloride is within the range of from 0.001 to 5% by weight based upon the weight of dry cellulose fibers.
 5. The process of claim 1 wherein the amount of said carbamoyl chloride is within the range of from 0.005 to 0.5% by weight based upon dry cellulose fibers.
 6. The process of claim 1 wherein both R1 and R2 are C18H37.
 7. The process of claim 1 wherein both R1 and R2 are C12H25.
 8. The process of claim 1 wherein said fibers are brought into contact with an aqueous dispersion of said carbamoyl chloride and an emulsifier in an effective emulsifying amount.
 9. The process of claim 8 wherein said emulsifier is a cationic compound.
 10. Cellulose fibers or material containing cellulosic fibers sized with a carbamoyl chloride having a general formula
 11. The cellulose fibers or material containing cellulosic fibers of claim 10 wherein the amount of said carbamoyl chloride is within the range of from 0.001 to 5% by weight based upon the weight of dry cellulose fibers.
 12. The cellulose fibers or material containing cellulosic fibers of claim 10 wherein the amount of said carbamoyl chloride is within the range of from 0.005 to 0.5% by weight based upon the weight of dry cellulose fibers.
 13. The cellulose fiber or material containing cellulosic fibers of claim 10 which further includes an emulsifier. 